To reduce flooding in St. Mary Parish, the Coastal Protection and Restoration Authority is pledging $80 million in funds to build a permanent floodgate across Bayou Chene.
Those funds, according to Governor John Bel Edwards, are from CPRA’s share of Gulf of Mexico Energy Security Act funds (GOMESA). The floodgate across Bayou Chene will help reduce backwater flooding in St. Mary Parish and portions of five other parishes.
“Backwater flooding in St. Mary and neighboring parishes has increasingly been a problem over the past decade as the Mississippi River and in turn, the Atchafalaya, has reached flood stage,” said Gov. Edwards. “Thanks to heroic, emergency efforts by the St. Mary Levee District, the worst was averted in both 2011 and 2016. Today, we are investing in this flood protection project to provide a permanent, long-lasting solution for the people of St. Mary’s Parish and the surrounding region.”
During extreme high water events on the Mississippi and Atchafalaya Rivers, Morgan City and communities in neighboring parishes are susceptible to flooding as water backs up and moves north up Bayou Chene.
According to a release, in the 2011 and 2016 events, the St. Mary Levee District constructed a temporary flood protection structure consisting of a barge floodgate, sheet pile floodwalls, rip rap, and Hesco baskets to prevent a six-parish area consisting of portions of St. Mary, Terrebonne, Lafourche, St. Martin, Assumption and Iberville Parishes from flooding. At the time, the structure prevented three feet of water from flooding these parishes.
CPRA says it began evaluating this project shortly after the 2011 flood event and fully incorporated it into both the 2012 and 2017 Coastal Master Plans. The agency put $5 million towards the engineering and design of this project and has now identified an additional $75 million from GOMESA for construction.
According to CPRA Board Chairman Chip Kline, the floodgate to be built on Bayou Chene south of Avoca Island can be closed when high water threatens, providing a permanent solution to protect citizens and property in the parish. “CPRA primarily looks to the GOMESA revenue stream to provide flood protection to coastal communities,” Kline said. When projects like this one can reduce risk for multiple jurisdictions and parishes, we know we are making the right investment.”
“The St. Mary Levee District has been working very closely with many partners to make this structure permanent and secure the necessary agreements to ensure the proper operations and maintenance of the structure,” said Bill Hidalgo, President of the St. Mary Levee District. “Now that the money is available, CPRA is fulfilling its commitment to the benefit of more than just St. Mary but the surrounding communities as well.”
As far back as 1973, temporarily sinking a barge in the Bayou Chene channel has been the emergency method of flood control in times of high water in the Atchafalaya. Once flooding subsides, the temporary barge floodgate is removed to allow for normal drainage and boat traffic. In 2011, some of the rock and sheet pile was left in place to accommodate another temporary barge in anticipation of future flooding which was needed in 2016.
St. Mary Parish President David Hanagriff said, “In 2016, it took 15 days to design, bid, build and install the temporary barge. It did the job but it wasn’t cheap and it had to be removed after the flood threat passed because it was blocking navigation. Having a permanent structure we can open and close is a better, smarter solution.”
The flood control project will feature steel receiving structures on the banks of Bayou Chene with a 400-foot barge gate that can swing into place and be sunk, providing an elevation against storm surge of 10 feet. It will include braced steel sheet pile floodwalls also elevated to 10 feet. The existing Avoca Road will be elevated to eight feet with an eight-foot earthen levee stretching from Avoca Road to the structure along the existing borrow canal. On the south side, an eight-foot earthen levee with geotextile fabric will connect the structure to the Tabor Canal levee that will be elevated to eight feet also, utilizing the existing berm and geotextile fabric. The planned weir structure at the end of Tabor Canal will have an elevation of six feet.
“We know this project is a good project, because we have seen it work twice now over the past decade to protect homes and businesses,” said Bret Allain, Louisiana Senator District 21. “Making the structure permanent and providing safety and security to portions of six parishes is a big win.”
To design the permanent structure on Bayou Chene, the St. Mary Levee District has contracted with APTIM, the firm that designed the 10,000-foot-long, 26-foot-high storm surge barrier across Lake Borgne as part of the Greater New Orleans Hurricane Storm Damage Risk Reduction System. APTIM has eleven offices in Louisiana. The construction contract will go to bid after the engineering and design is complete.
“This announcement is the culmination of years of effort which has finally produced actual dollars for construction of critical protection for Morgan City, east St. Mary and lower St. Martin from backwater flooding,” said state Rep. Sam Jones, Louisiana State Representative District 50. He continued, “Our presence here today signifies the importance of perseverance.”